Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	$ 2,322	$ 3,017	$ 4,380	$ 5,709
Net Income	(116)	(71)	(161)	(178)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains and Losses on Available for Sale Securities
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other Nonoperating Income (Expense)	0	0	0	0
Total before tax	0	0	0	0
Provision for Income Taxes	0	0	0	0
Net Income	0	0	0	0
Reclassification out of Accumulated Other Comprehensive Income | Accretion of Net Retirement Plan Prior Service (Cost) Credit
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other Nonoperating Income (Expense)	(55)	3	(54)	6
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss)
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other Nonoperating Income (Expense)	(103)	(181)	(163)	(359)
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(158)	(178)	(217)	(353)
Provision for Income Taxes	42	107	56	175
Net Income	$ (116)	$ (71)	$ (161)	$ (178)